Instantaneous switch



.Ndv. 1a, 1924.

A. LEWERENZ INSTANTANEOUS SWITCH Filed May 28. 1923 2 Shuts-Shut 1 Nov. 18,

- 1,516.195 A. LEWERENZ INSTANTANEOUS SWITCH r11: May 28; 1923' a Shun-Shut 2 M Fl 9.6. 36

v Nov; 18, 1924.

umrao's'rA-ras} PATENT OFFICE.

anrmin LEWEBENZ, or nnnnm, cmm..

INSTANTANEOUS SWITCH.

. ppumion lied Kay as, 192:. Serial :0. 842,009.

switches have been built already which Work under, the influence or,

the heat and which comprise a strip of sheet metal consisting of two metals possessing difierent coefiicients of expansion due to heat. The movements made by these double metal strips when the temperature changes 1 are infinitesimall small and extremely slow owing to slow a ission of the heat so that during the interrupting of the circuit electricity flows still over for a certain time with production of sparks, whereby the contact arts of such switches are rapidly destroyed. ith many switches of this type the danger is present that the circuit might be accidentall interrupted if the switch is shaken.

With t e switchesof known t e the distwice for which the switch trave s could be made only disproportionately1 small so that it was not posslble to control ilgher voltages with'such switches owing to -t e danger of the untimely sparkin over. a

so For many devices, or instance of heatin apparatus ofsmaller size, the dimensions 0 the switch were far too great so that] the heat ca acity of-the switch influenced uns favorably the distribution of the heat and 86 consequently the accuracy of the regulation.

The heat switch according to the resent invention is an instantaneous switc and combines, the ;following essential advanit is of -very small dimensions.

- It has a com aratively great switching path with sma difi'erences betweenthe switching-in and switchingelf temperatures.

It switches instantaneously.

I 46 The invention is illustrated by way of example on the accompanying drawing, where 1 shows in elevation an instantaneous switc according to the invention. Fig. 2 is a cross section on'lineIL-II of enlarged scale.

'2 is inserted at/3. The bi-hietal stri Igaging, the one 13, with the indentation 6 Fig. 3 is a part elevation of the instantaneous switch shown in Fig. 1 but on much Fig. 4, 5 and 6 show each a sli ghtlyimoditied form of construction of an instantaneous switch.

Figs. 7 and 8 show in side elevation and front view respectively aconstructional detail of another form of construction.

In a casing an oscillably mounted element, for instance an elastlcbi-metal strip consists of two difi'erent kinds 0 metal, or instance at the left of-brass and at the right 66 of iron. At the free end of'the strip a kind of head4 is formed, for instance by bending of the end.5 which has an indentation 6. At the one side of the casing 1 a contact member, consisting of a'contact' screw 7 with contact in 8 is inserted in the easing 1 insulated y meanb of insulating disks 9, said contact member 'formin an abutment for the bi-metal strip 2 att e one side, the abutment at the other side being formed by a screw 10. At the point where the contact pin 8 is situated a separate contact plate 11 is arranged on the bi-metal strip in order to ensure a secure contact.- The contact member. 7 is connected with the one pole of a source of current and the casing 1 is connected with the other pole of the source of current.

It is essential that in the casing 1 an elastic su ort, in the form of construction sh'ownin igs.'13 a helical or spiral sprin 12, is arranged which acts'upon the free end 4: of. the elastic bi-metal strip 2 and which is designed to reduce, at the liftin of the bi-metal strip oi the contact meln r7 or of the contact pin 8 of the same, the resistance against this lifting ofi and, after the bi-metal strip has got beyond the middle position, to assist the lifting of so that the opening1 of the contact is effected instantaneous y and not slowly and with sparking over.

The spiral spring12 has at: each end a sharp hardened point 18 respectively 14 en-. "0 of thebi-metal strip and the other 14 with an indentation 15 of an adjusting screw 16'.

By adjusting the'screw 16 the difierence of tem erature between the switching in and the switching out is altered, this difference of temperature increasing with the ressure of: the elastic support 12 upon the rec end j perature at which the interruption of contact has to take place.

The operation of the instantaneous switch is as follows:

7 Suppose the reg llllatingflscrews 2 be tightened so that t e bi-metal stri is in contact with the contact pin 8 of t e contactmember 7 with a determined pressure, the circuit being thus closed, The elastic support 12 exerts in this case a determined pressure on the strip approximately in the lon udinal direction of this stop whereby, at t e normal position, the contact pressure of the stri upon the contact pin 8 is; increased. f the strip' is heated the force which tends to lift the strip from the control in 8 will just overcome at a determines moment the force of the elastic support 12,,s0 thatthe strip 2 begins to lift off the contact pinQfl During this lifting ofthe strip the component diminishes wit which -the elastic support acts in the sense of pressing the element 2',on the contactfpin 8. This component will become zero at the instant when the oscillating element 2 moves tlirou h the middle position M-M, and, if t e movement of the oscillating element 2 continues, it will exert an increasing force which assists in the liftin of the element 2. ,The'forces of.the elastic support 2 acting upon the oscillating element 2 "change absolutelyuniformly, viz, roportionally to the displacement between t e 'abutments.

Experiments with and without elastic support have shown that the amplitude of the oscillating movement of element 2 at equal differences of temperature is considerably greater if the elastic support 12 is inserted than without this supportfprovided the elastic amplitude of the oscillating element 2 and'the pressure of the elastic support 12 are in a determined relation.

. This relation may be ascertained easily by adjusting the screw 16.

In the form of construction shown in Fig. 4 an elastic 'bi-metal. strip 17 is used as oscillating element which is adapted to oscillate, same as in the form of construction shown in Figs. 1-3, between an adjustable contact member 18 and a stop screw 19.

A transverse beam 22 is mounted in a casing 29'on a knife ed e 21, a spring 23 acting upon the ends .0 said beam. The tension of the spring 23 may be varied by means of-a screw 23. Between the free end tween an adjustable contact member 27 andan adjustable stop 28 An elastic su port 29 of similar construction as shown in igs.

1-3 acts upon the free end of the oscillating element 25. s

I The oscillating element 25 is exposed on the one side to the action of a sprin 30 which has the tendency to press the osci lating element a ainst the contact member and \it is on the ot er side under the influence of a wire 31 which. is attached to a body possessing a different coefiicient of expansion. In the form of construction shown this wire,

for instance a steelwire, is fixed to a screw cap 32 of a brass tube 33 connected with the casing '26. 1 The lifting of the -off the contact 27 is controlle by a force which results from the difference of the longitudinal expansion-of the steel wire 31 and of the brass tube 32 at increasing heating, the lifting 03 being facilitated in the manner descrlbed bv the elastic support 29 and assisted in such a manner that the lifting ofi takes place instantaneously. In the form' of construction shown in Fig. 6 an elastic bi-metal strip in form of a spiral 34 is fixed with the one end in the casing 35. The. other end of the bi-metal strip is attached to an oscillating element 37ll110l1l1tedon a knife edge 36 and it has the tendency to press normally this element against a contact member 38.

An elastic support '39 and an adjustable stop 40 are arranged as in Figs. 1-3 and 5.

In the form of construction shown in Figs. 7 and 8 an elastic bi-metal strip 41 serves as oscillating element, said strip being adapted to oscillate between a contact rffmber 42 with contact pin 43 and a stop An elastic su ranged not in a lgnment with the bi-metal strip 41,but perpendicularly to the longitudinal axis 'of said strip and acts on the side edge of this strip. The lifting off from thecontact member is in this manner also facilitated and assisted.

, on 'oscillatin element 25 Ito port 45 is in this case ar- The tension of the elastic support 45 and i for the oscillating elementwhich are for instance formed by the ends of the contact pin 8 and ofthe screw 10 (Fig. 3) are preferably arranged atboth sides and at e ual distances from the middle axis M-M, tliis bein however not absolutely necessary asthe distances of the strips ma be unequal, the apparatus working even if th strips are situated at the same side of the middle axis.

I claim.

1. An instantaneous thermo-sw-itch for electric lines comprising in combination, a contact member connected to one pole of a source of current, temperature responsive means connected -to the other pole of the source of current and including a stripshaped switching'element for closing and interrupting the circuit, pressed against said contact member at normal temperature by a force andc being adapted tomove awayfrom the contact member to overcome said force for interrupting the circuit at increasing temperature, an elastic support acting upon the free end ofsaid'switchingelementfor assisting the latter to rapidly move away from the contact member only after said element has'moved a certain distance away from the contact member, and a stop for limiting the movement away from said member.

2. An instantaneous thermo-switch for.

electric lines comprisingv in combination a contact member connected to one pole of a source of current, an elastic strip clam ed,

at one end and connected with the ot ier pole of the-source of current, and pressed by spring power at normal temperature against the said contact member, said strip at increasin temperature being adapted to move away rom the contact member for interrupting the circuit, an elastic support arranged approximately in the place of said strip and actin upon the free end of the latter for rapi ly moving the strip away from the contact member only after said strip has moved a certain distance away from the contact member, means for regulating the spring pressure of said elastic sup-- port, and a stop for limiting the movement 7 spring arranged approximately in a gnment "with the by-metal strip and having at each end a sharp -point,a regulating screwfhatf.

ing an indentation receiving one 0 points of said spiral spring, a head at the free end of the by-metal strip havingan indentation receiving the other point of said spiral spring, said spiral spring being adapt.- e

to oppose the -movement of e strip I away from the contact pin to a certain point I and tothen assist the further movement of the strip away from the contact pin.

4. A switch as claimed in claimB including-means for pressing the by-metal strip against the contact pin.

5. An instantaneous electric lines comprisin in combination a contact screw connecte with one'pole of a source of current, a casing in which said contact screw is mounted, means for insu lating. said screw from said casing, an elastic by-metal strip connected-with the other "pole of. the source of current and having one of its ends clamped in the casing, the other end of the stri being movable toward and away from sai screw, a contact plate on the free end of the strip pressed by the resiliency of the latter at normal temperature against said contact pin, a s iral spring arranged -approximately in a ignthermo-switch for.

ment with the by-metal strip and having at each end a sharp point, a re lating screw having an indentation receivingone of the points of said spiral spring, a head at the free end of the by-metal strip having an indentation receiving the other point of said Y spiral spring, said sprin being adapted to resistthe movement oft e strip away from the contact screw to a certain-point and to assist the further movement of'the strip away from this point, a screw sto for limiting the movement of the by-meta strip, and a screw for regulatin the pressure with which said by-metal strip is pressed against said contact screw.

6. vAn instantaneous eluding a contact member adapted to be connected to one pole of a source of current, temperature responsive means including an oscillating conductor strip adapted 'to be connected to the other pole of the source of current and to bear wit tioning to move the strip away from the contact member when the temperature increases, and resilient means engaging said the-movement of the strip away contact memb'er'up to a certain point and then to rapidly move the strip away from y this point.

In testimony whereof I afiix'my signature in presence of a witness;

Witness:

- E. Hom'znmum.

its free end at nor mal temperature against the contact member, said temperature responsive means functherinoswitch in- I As'rnUR EwEREnz,

strip and functioning to decreasingly resilet rom t e 

